By inflating cushions, in particular for supporting persons, it is very important that the cushion contains the correct amount of air such that it provides optimal support while at the same time the cushion has an appropriately soft and yielding surface. Therefore it is important that the cushion is not inflated too hard, as in such cases it will have a negative effect in relation to supporting persons with the risk of pressure marks on the skin with subsequent pressure sores in the tissue. At the same time it is also important that there is exactly as much air in the cushion so that the skin on the hard projections of the body (heels, elbows, bones etc.) is not resting directly on the hard support under the cushion.
There are cushions for this application that are inflated manually or by an electric pump, but there is just the relatively great disadvantage that it is almost impossible to indicate a suitable degree of inflation. Actually, it is so that each staff member build their own experience, but since it is not always the same person that operates the individual patients, it is very difficult to offer uniform treatment and support with the cushions in question.
The correct amount of air in the cushion by optimal support corresponds to the cushion containing air with a modest overpressure or with a pressure corresponding to atmospheric pressure. In principle, this means that more air can be in the cushion, but with normal inflation there is no measurable pressure difference between the air inside the cushion and the ambient air outside the cushion. Also, this means that normally used indicators for indicating pressure in the inflated article—here a cushion—cannot be used for this purpose. Similarly, it will not be possible to use certain time intervals for inflating the individual cushions as different pumps with different output are used for inflating the same type of cushions.
Frequently it is therefore a challenge to find the correct amount of air for the cushion such that an optimal support is provided.
US 2014/0130261 A1 discloses an example of a cushion inflated by air, and which via a manual pump or an electric pump can be inflated with a given pressure. In a variant of this air cushion it may include an integrated electronic pressure sensor transmitting a signal about the actual pressure to either a display or a control unit. However, this is a built-in electronic device which, all things considered, comes at a cost, in this case justified by the fact that the air cushion can be used many times and thus is not a disposable article.